Separable two-part magnetic connector



March 21, 1961 F. BUDRECK 2,975,497

, SEPARABLE TWO-PART MAGNETIC CONNECTOR Filed Oct. 7, 1959 2Sheets-Sheet 1 lllllLJ 7 II III/ll DIIIDLVIII/III/ 92 INVENTORI FRANCESBuoaacz March 21, 1961 F. BUDRECK SEPARABLE TWO-PART MAGNETIC CONNECTOR2 Sheets-Sheet 2 Filed Oct. 7, 1959 INVENTOR Fmwcss Buoaacx ATTY.

2,975,497 SEPARABLE TWO-PART MAGNETIC CONNECTOR Frances Budreck,Chicago, 111., assignor to Monarch Tool & Machinery Co., Chicago, 111.,a corporation of Illinois Filed Oct. 7, 1959, Ser. No. 845,026

'5 Claims. (Cl. 24-201) The improved separable two-part magneticconnector comprising the present invention is versatile in itsapplication and is capable of many uses. The connector has beenillustrated and described herein as being in the form of a separable keychain connector which is designed for use in connection with the parkingor storage of automobiles and other motor vehicles in public parkinglots, garages and the like. Such separable key chain assemblies consistof two independent key chains, one of which is adapted to retain asingle ignition key and the other of which may retain a reserve ignitionkey and a glove compartment and trunk key. The two chains are releasablyconnected together, usually by a push-pull snap connection so that uponleaving an automotive vehicle in a public parking place, the singleignition key may be left in the ignition lock for use by the attendantwhile the chain containing the reserve ignition key and glovecompartment and trunk key may be retained by the vehicle owner. Theattendant is thus precluded from access to either the glove compartmentor the trunk but he is able to operate the vehicle.

The separable two-part magnetic connector of the present invention iscomprised of a magnet assembly which, as a whole, constitutes one of theparts, and an armature assembly which, as a whole, constitutes the otherpart. -When the separable connector of the present invention is employedin this manner as a detachable key chain holder, the reserve keys arepreferably associated with the permanent magnet assembly while thesingle ignition key is associated with the armature assembly. Since theautomobile owner retains the permanent magnet assembly at all times,i.e., singly when the armature assembly is left in the vehicle, and incombinationwithv the armature assembly when both parts are inhis-possession, he has at all times at his disposal a small permanentmagnet assembly which he may use as he sees fit to pick up smallmagnetic articles such as pins or nails, to test or distinguish ferrousarticles or materials from non fer rous articles or materials, to attachthe reserve key chain in a concealed place, as, for example, benea-ththecowl ;or a fender if he does not prefer to carrythe assembly with, orotherwise to use the magnet in any manner in which smallpermanent magnetassemblies are customarily used.

The invention is, however, capable of a wide variety of other uses-andpermanent magnet and armature assemblies constructed in accordance withthe principles of the present invention may be employed as arefrigerator, cabinet, or other door latch; Another specific use of thisnature which has been contemplated is in connection with the provisionof latches for trailer doors or doors on other moving vehicles wherelooseness which may develop in the hinges would ordinarily lead torattling or squeaking of the door. Because, as will be set forth indetail presently, the present connector makes provision for preventionof lateral or transverse shifting of-the. armature relative to themagnet, any parts which are-fixedly attached to the permanent magnetUnited States Patent connector and armature assembly respectively willbe held against shifting movement relative to each other in a lateraldirection or, in fact, in any direction what soever. This prevention oflateral shift between the permanent magnet and its armature, in apermanent magnet and armature assembly of this general character,constitutes one of the principal features or objects of the presentinvention and thus renders it especially useful as a door lock on movingvehicles;

It is another object of the invention to provide an assembly of thegeneral character briefly outlined above which involves a noveldisposition of the magnet, its pole piece, and the armature, these partsbeing designed so that the flux in the magnet-holding circuit isconcentrated in a small contact area, thus making possible a high fluxdensity and attaining increased magnet-holding power. By virtue of suchincreased holding power, the overall size of the assembly may be verymaterially reduced.

Numerous other objects and advantages of the invention not at this timeenumerated, will become more readily apparent as thefollowing'description ensues.

In the accompanying two sheets of drawings forming a part of thisspecification, one illustrative embodiment of the invention has beenshown.

In these drawings:

Fig. 1 is a perspective view of a separable key chain assembly employingthe improved permanent magnet and armature assembly of the presentinvention;

Fig. 2 is a side elevational view of the structure shown in Fig. l withthe two parts of the assembly slightly separated; 7

Fig. 3 is an enlarged sectional view taken substantially along the line3-3 of Fig. 2;

Fig. 4 is an enlarged sectional view taken substantially along the line44 of Fig. 2;

Fig. 5 is an inside end view'of the structure shown in Fig. 3;

Fig. 6 is an inside end view of the structure shown in Fig. 4; t

Fig. 7 is a longitudinal sectional view taken substantially centrallythrough the permanent magnet and armature assembly of Fig. l;

Fig. 8 is an exploded perspective view of the magnet assembly; and

Fig. 9 is an exploded perspective view of the armature assembly.

Referring now to the drawings in detail, and in particular to Figs. 1and 2, the separable key chain assembly illustrated herein for exemplarypurposes has been designated in its entirety at 10. The assemblyinvolves in its general organization a permanent magnet assembly 12 andan armature assembly 14. The armature assembly has associated therewitha conventional ball and link key chain carrying an automobile ignitionkey 18, while the permanent magnet assembly has associated therewith asimilar key chain 20 carrying a reserve ignition key 22 and a trunk lockkey 24. As will be described in greater detail presently, the magnetassembly 12 and armature assembly 14, when disposed in approximatelongitudinal alignment and position of close proximity, are attracted toeach other so that the two key chains 16 and 20 are held together as aunit, but the same may be separated from each other merely by manuallypulling the magnet assembly and the armature assembly apart so that thearmature associated with the latter assembly moves out of the field ofthe magnet associated with the former assembly.

The key chains 16 and 20 and the various keys illustrated herein areconventional and no claim-is made to any novelty associated therewith."Neither is any noveltyf inasmuch as separable key chains designed forthe same purpose and embodying mechanical spring detent means for theirseparation are well known in the art. The invention consists rather'inthe novel construction, combination, and arrangement of parts of thepermanent magnet assembly 12 and its associated armature assembly 14,these parts having utility in connection'with structures other than keychain holders.

' Referring now specifically to Figs. 3, and 7, the permanent magnetassembly may assume various external configurations, but in theembodiment illustrated herein, it is of circular cross sectional shapethroughout. The assembly includes four principal parts including anouter generally cup-shaped shell or holder 30, an inner cupshaped polepiece and magnet retainer 32, a permanent magnet 34, and a second polepiece 36. The holder or shell 30 is preferably formed of a non-magneticmaterial such as a suitable thermoplastic or thermosetting resin. Thetwo pole pieces 32 and 36 are formed of magnetic material such as mildsteel. The magnet proper 34 is a ceramic magnet of the mixed ferritetype, such magnets being a comparatively recent development in the fieldof permanent magnet construction and possessing greatly improvedmagnetic properties over permanent magnets which are constructed ofmetallic alloys.

One such magnetic material capable of being employed in connection withthe present invention for construction of the magnet 34 is the materialknown as Indox, a development of the Indiana Steel Products Company ofValparaiso, Indiana. This barium-ferrite material is characterized bythe fact that it is electrically nonconductive. The material isextremely resistant to demagnetizing influences and evidences very loweddy current losses. Indox is a magnetic material which exhibitsextremely high coercive force, a low remanence and high permeability.Because of these characteristics of this permanent magnet material, themagnetic length thereof need be but a fraction of that required for theferrous alloys in attaining the same magneticpull for a given magnetsize. Where barium-ferrite ceramic materials are concerned, magneticstability is pronounced and permanent magnets of this character maintaintheir magnetic strength despite weakening influences such as contactwith extraneous magnetic fields and frequent removal and replacement ofthe magnetic armatures. Additionally, Index and like ceramic materialsare relatively light as compared to the magnetic alloys.

As a magnetic material for holding purposes, the shape characteristicsand small sizes which Indox and similar materials may assume for anygiven attractive power leave little to be desired. For example, suchmagnetic materials satisfy the requirements of releasable holdingdevices for refrigerator doors and the like where space is at a premium,where high holding power is required, and where frequent armatureattraction and release is encountered. Ceramic magnets of this type areextremely effective even when they are of thin wafer-like design and,accordingly, the magnet 34 illustrated herein is of relatively thin,flat construction and its association in the assembly will be describedin greater detail presently.

The outer shell 30 includes a shallow flat cup portion having a fiatbottom wall 40 and an upstanding cylindrical side wall 42. The medialregion of the bottom wall 40 is provided with a stem 44 having with adiametrically extending hole 46 therethrough near the distal endthereof, the marginal regions of the hole being flared as at 48 for keychain clearance purposes.

The combined pole piece and magnet retainer 32 (which hereafter will bereferred to as a pole cup) includes a circular bottom wall 50 and anupstanding cylindrical side wall 52. The pole cup 32 is nested withinthe cup portion of the shell 30 with a close fit as clearly shown inFig. 3 and, if desired, it may be cemented within the shell.

The ceramic magnet 34 is in the form of a relatively thin disk which ispreferably, but not necessarily, provided with a central opening or bore60 therethrough. The magnet is magnetized as shown in Fig. 3 to providepoles of opposite polarity on the upper and lower magnet faces 62 and64, respectively. The lower magnet face 64 is cemented to the bottomwall 50 of the pole cup 32.

The magnetic pole piece 36 is in the form of a flat circular disk whichis centered coaxially on the upper face 62 of the magnet and is cementedthereto. In the assembly, this pole piece serves as a protective shieldfor the face 62 of the magnet.

Referring now to Fig. 4, the armature assembly 14 comprises two parts,namely, an outer shell 70 and an inner armature 72. The shell 70 issubstantially identical with the shell 30 of the assembly 12 and itincludes a bottom wall 74, an upstanding cylindrical side wall 76, and astem portion 78 having a key chain receiving opening 80 therethrough.The armature 72 is in the form of a mild steel cup-shaped membersubstantially identical with the pole cup 32 of the assembly 12 and itincludes a circular bottom wall 82 and an upstanding cylindricalcontinuous side wall 84. The two parts 70 and 72 are nested together ina manner similar to the nesting of the parts 30 and 32 and the innerpart is cemented to the outer part in the same manner.

It is to be noted at this point that the pole cup 32 is provided in thecircular rim portion of the side wall 52 with a series of four equallyspaced notches while the circular rim portion of the side wall 84 of thearmature 72 is similarly provided with a series of four equally spacednotches 92.

Referring now to Fig. 7, it will be seen that when the parts aremagnetically coupled, the circular rim region of the cylindrical wall 84of the armature encompasses the outer region of the magnet 34 with verylittle clearance between the parts so that lateral shifting of thearmature and magnet relative to each other is precluded. Prevention oflateral shifting of the armature with respect to the magnet when thearmature and magnet are in their magnetically coupled relation isdirectly attributable to the fact that the over-all width or diameter ofthe rim or cylindrical side surface 68 of the magnet 34 is but slightlyless than the internal diameter of the armatureside wall 84. The extremerim portions of the two cupshaped members 32 and 72 make circular linecontact with each other and are held together by magnetic attraction.The extent of magnetic attraction between the two rim portions ismaterially enhanced by virtue of the fact that the thin rim of the polecup 32 effectively concentrates the flux in a narrow band. Such magneticattraction is further enhanced due to the fact that the meeting rims ofthe pole cup 32 and armature 72 lie in a plane which is parallel to andsubstantially midway between the planes of the magnet pole faces 62 and64 respectively where flux concentration is at a maximum. With the partsthus magnetically coupled, a small clearance exists at between the outerface of the pole piece 36 and the bottom wall 82 of the armature andacross which clearance space there exists a strong magnetic pull.

The high degree of magnetic pull which the two assemblies 12 and 14 arecapable of exerting each upon the other is to a large extent predicatedupon the fact that high flux concentration is effected in the rim of thecylindrical wall 52 of the pole cup 32 so that the flux path is throughthe two cylindrical walls 52 and 84 and through bottom wall 82 of thearmature across the narrow air gap created by virtue of the clearanceregion 100. This air gap 100 is effective over a wide circular areawhere the opposed faces of the pole piece 36 and bottom wall 82respectively approach each other but do not actually meet.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings. or

described in this specification as various changes in the details ofconstruction may be resorted to without departing from the spirit of theinvention. Only insofar as the invention has particularly been pointedout in the accompanying claims is the same to be limited.

Having thus described the invention what I claim as new and desire tosecure by Letters Patent is:

1. A separable two-part magnetic connector comprising in combination, amagnet assembly and a cooperating armature, said magnet assemblycomprising a permanent magnet of the barium-ferrite type and in the formof a flat disk presenting oppositely facing pole faces of oppositepolarity and a narrow outer rim, and a pole cup of magnetic material andhaving a bottom wall and a cylindrical side wall, the magnet beingnested within said pole cup and having one pole face thereof bonded tosaid bottom wall, the longitudinal extent of said cylindrical side wallbeing slightly less than the thickness of the disk whereby the portionof the magnet embodying the other pole face projects outwardly beyondthe rim of said cylindrical side Wall, said armature comprising acup-shaped member formed of magnetic material and having a bottom walland a cylindrical side wall, the longitudinal extent of the armatureside wall being slightly greater than the longitudinal extent of thedisk less the longitudinal extent of the side wall of the pole cup, thediameter of the two side walls being substantially equal, and said rimof the disk having an overall width slightly less than the diameter ofthe armature side wall, so that when the magnet and armature aremagnetically coupled to the fullest extent of which they are capable,the pole cup will be telescopically received over the outwardlyprojecting portion of the magnet, the bottom wall of the armature willbe slightly spaced from said other pole face of the magnet and liewithin the magnetic field thereof, the rim portions of both cylindricalside Walls will be in substantially coextensive physical contact andalignment, and the projecting portion of the magnet will be in closeproximity to the rim portion of the side wall of the pole cup andprevent shifting of the armature relative to the magnet in a directionto cause misalignment of said rim portions.

2. A separable two-part magnetic connector comprising in combination, amagnet assembly and a cooperating cup-shaped armature of magneticmaterial, said magnet assembly comprising a permanent magnet of theceramic type and in the form of a flat circular disk presentingoppositely facing pole faces of opposite polarity and a cylindrical sideface, and in addition a pole cup formed of magnetic material and havinga bottom walland a cylindrical side wall, the magnet being nested withinsaid pole cup and having one pole face thereof seated on said bottomwall, the height of said cylindrical side wall being less than thethickness of the magnet whereby the portion of the magnet embodying theother pole face projects outwardly beyond the rim of said cylindricalside wall, said armature having a bottom wall and a cylindrical sidewall, the magnet normally having its outwardly projecting portiontelescopically nested within the armature with the bottom wall of thearmature attracted to said other pole face by its close proximitythereto, the height of the side wall of the armature being less than thethickness of the magnet, the combined height of both side walls being atleast equal to the thickness of the magnet and the diameter of the twoside walls being approximately equal whereby the rims of said side wallsnormally meet in substantially coextensive edge-to-edge relationship andalignment at a medial region substantially midway between the planes ofsaid pole faces, the diameter of the magnet being slightly less than theinternal diameter of the armature side wall whereby lateral shifting ofthe armature relative to the pole cup and consequent misalignment ofsaid rims is prevented.

3. As a new article of manufacture, a quickly and readily separabletwo-part magnetic connector comprising a .magnet assembly and acooperating armature, said magnetio assembly embodying a permanentmagnet of the ceramic type and in the form of a flat disk presentingoppositely facing pole faces of opposite polarity and an outer rim, andin addition a pole cup formed of magnetic material and consisting of abottom wall and a cylindrical side wall, the magnet being nested withinsaid pole cup and having one pole face thereof seated on said bottomwall, the longitudinal extent of said cylindrical side wall of the polecup being less than the thickness of the magnet whereby the portion ofthe magnet embodying the other pole face projects outwardly beyond therim of said cylindrical side wall, said armature comprising a cup-shapedmember formed of magnetic material, consisting of a bottom wall and acylindrical side wall, and adapted telescopically to receive theoutwardly projecting portion of the magnet, the armature side wallhaving its mean diameter substantially equal to that of the pole cupside wall and being adapted when the magnet and armature aremagnetically coupled to their fullest extent to have its rim abutdirectly against the rim of the pole cup side wall, the rim of themagnet having an over-all width or diameter but slightly less than theinternal diameter of the armature side wall in order that when saidmagnet and armature are magnetically coupled to their said fullestextent the armature is prevented from shifting with respect to themagnet in a direction to cause misalignment of the rims of said armatureand pole cup side walls, the longitudinal extent of the armature sidewall being slightly greater than the thickness of the magnet less thelongitudinal extent of the side wall of the pole cup in order that whenthe magnet and armature are magnetically coupled to their fullest extentthe bottom wall of the armature is slightly spaced from said other poleface of the magnet but lies within the magnetic field thereof.

4. A separable two-part magnetic connector as set forth in claim 3 andwherein the side walls of the pole cup and armature are the same inlongitudinal extent and are of such combined longitudinal extent thatwhen the magnet and armature are fully magnetically coupled the abuttingrims thereof lie in a plane which is disposed substantially midwaybetween the pole faces of the magnet.

5. As a new article of manufacture, a quickly and readily separabletwo-part magnetic connector comprising a magnet assembly and acooperating armature, said magnet assembly consisting of a disk-likeceramic magnet structure having end parts with oppositely facing polefaces of opposite polarity and in addition an outer cylindrical rim,said assembly also embodying a pole cup formed of magnetic material andconsisting of a flat bottom wall and a cylindrical side wall, the magnetstructure being nested within, and fixedly connected to, said pole cupand having one end part thereof seated against said bottom wall of thepole cup, the longitudinal extent of the side wall of the pole cup beingless than the thickness of the magnet structure whereby the other endpart of said structure projects outwardly beyond the rim of saidcylindrical side wall, said armature comprising a cupshaped memberformed of magnetic material, consisting of a flat bottom wall and acylindrical side wall, and adapted telescopically to receive theoutwardly projecting other end part of the magnet structure, thearmature side wall having its mean diameter substantially equal to thatof the pole cup side wall and being adapted when the magnet structureand armature are magnetically coupled to their fullest extent to haveits rim abut directly against the rim of the pole cup side wall, the rimof the magnet structure having its diameter but slightly less than theinternal diameter of the armature side wall in order that when saidmagnet structure and armature are magnetically coupled to their saidfullest extent the armature is prevented from shifting with respect tothe magnet structure in: a; direction tocause'misalignment-of the :fimSO thearmature-and polecup side wall; the lqngitudinalrextent of thearmature sidewall being slightly greater than the thickness of saidoutwardly projecting other end part of: the magnet structure in orderthat when the magnet andarmature are magnetically coupled to their saidfullest. extent the bottom Wall of the armature is slightly spaced fromthe other pole face of the magnet but lies within the magnetic fieldthereof.

References. Cited in the ,file rof this patent UNITED STATES PATENTSAvedon Sept. 27, 1949 Feibelman Dec. 30,1952; Watson MayVS, 1953Gerhardt May 11, 1954- 'Holmes Oct. 7, 1958

